Muffle.



' J. B. FARQUHAR.

MUFFLE.

APPLICATION FILED DEC. 18. 1915.

LQ69,%?U Patented June 11, 1918.

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(W lli specification of Letters ente d e hane Jill,

Application riled hecember is, 1916. Serial No. 13?,t57/l.

To all whom it may concern:

Be it known that l, James B. FARQUHAR, a citizen of the Dominion of Canada, residing at Vancouver, in the Province of British Columbia, Canada, have invented certain new and useful Improvements in. Mufides, of which the following is a specification.

This invention relates to an improved construction in a mums of that class used by assayers but applicable to any inuiifle applied for any purpose.

These mulides are commonly formed with the door, walls and arch integral and owing to irregular stress of expansion, they are subject to fracture in the walls generally ad jacent the junction of the 'fioor thereto. lit is to remove this cause of fracture that the subject matter of this application has been devised.

v The invention is particularly described in the following specification, reference being made to the drawings by which it is accompanied, in' which:

The figure is a perspective view of a mue constructed in accordance with my invention.

In these drawings 2 represents the floor, 3 the-walls and roof of the muffle, a being the closed end which is apertured at 5 to permit escape of the fumes given off from the material being treated within the muflie. instead of, as is usual, forming the floor integral with the walls and roof, which integral construction is the cause of frequent fracture, the door 2 is formed as a separate piece onto which the lower edges of the walls 3 and back end 4 are seated.

To retain the walls in position on the door 2 and prevent intrusion of the flue gases within the mufie at the joint, the bottom is formed With-a roove 6 to receive the lower edges of the Walls and back, in which groove the thickness of the walls and back are an easy lit to permit expansion of one part in relation to the other.

The outer edge of the groove 6 or inner edge of the raised bead 7, may be beveled and the space 8 so left is filled with a suitable refractory sealing material such as bone ash. The heat being" applied to the outer side of the mufie, the greater expansion of the outer side will tend to force the lower: ends of the w 3 inwa" d, while the direct expansion of be outward. ting; the middle in can described, this unequal expansion of one part in relation to another imposes no destructive stress in the side walls, and in consequence a greater life is insured for the mufile, while no provision of the groove 6 or lip i locates the upper part definitely in. relation to the lower and prevents indraft at the joint which is rendered more effective by a sealing material applied to the joint,

ll am aware that prior to my invention mue furnaces have been sectionally constructed to provide for the efiect of unequal expansion under heat, and to avoid having parts of exceptional size or weight for transport. i am also aware that mufie furnaces have been designed with an inner or mufhe chamber sectionally constructed as a part of the furnace, but where this has been done vthe sectional construction has been a necesv sary requirement in attaining the deslred object of providing an inner or muifie chamher with thiclrer roof to prevent accession of heat therethrough, and thereby obtain a more uniform distribution of heat within the inner'chainber, and not to provide for the opposite expansions of the door, walls and roof of a mufde per 86. in a muffle furnace where the outside exposed to the atmosphere and the inner side to the extreme heat of a furnace the requirement of proo viding for the opposed expansions is obvious but with a mufie as se arate arti cle of manufacture, the requirement is not so obvious as the entire muffie is inclosed within the furnace, but the same conditions of opposed expansions prevail in a muifieas in a muifie furnace, though not to such .an eX treme degree, as the heat of the furnace which passes through the mufiie walls is ap plied from the outside, so that the outer side must be heated in excess of the inner side and opposed stresses are imposed which lead to frequent fracture.

Manufacturers of mufies have endeavored to meet the defect by rounding the corners at the junctions of the floor and roof to the walls and by thickening the walls toward the floor junctions where the opposed errpansions meet, but within my knowledge no attempt has been made to meet the defect by sectional construction leaving each part free to ezrpanu with provision for locating one ii; on the other and for closing the described my in- I it'll lllli as nea and desire to be protected in by Letters Patent, is:

A mume constructed in tWo parts, one an. arched Wall and roof member, and an integrally formed end Wall, the other part comprising the floor member and being" provided With an upwardly projecting edge bead to receive the bottom edge of the Wall of the first part, the inner edge of said bead being beveled outwardly to provide a space haeaat/o' at the outside of he wall, and a sealing ma terial located in said space, said floor mem-- her also being recessed to receive the lower edge of the Walls of the first part, said re- 15 cess at the inner side having a vertical Wall surface against which the side of the lower edge of the Wall of said first part rests, all being arranged substantially as shown and for the purpose described. 7

In testimony whereof I a my signature.

" JAMES B, FARQ. 

